REVIEWOpenAccessCircRNAsinanticancerdrugresistance:recentadvancesandfuturepotentialTianweiXu1†,MengweiWang1†,LihuaJiang1†,LiMa1†,LiWan2,QinnanChen1,ChenchenWei1*andZhaoxiaWang1*AbstractCircRNAsareanovelclassofRNAmoleculeswithauniqueclosedcontinuousloopstructure.CircRNAsareabundantineukaryoticcells,haveuniquestabilityandtissuespecificity,andcanplayabiologicalregulatoryroleatvariouslevels,suchastranscriptionalandposttranscriptionallevels.NumerousstudieshaveindicatedthatcircRNAsserveacrucialpurposeincancerbiology.CircRNAsregulatetumorbehavioralphenotypessuchasproliferationandmigrationthroughvariousmolecularmechanisms,suchasmiRNAsponging,transcriptionalregulation,andproteininteraction.Recently,severalreportshavedemonstratedthattheyarealsodeeplyinvolvedinresistancetoanticancerdrugs,fromtraditionalchemotherapeuticdrugstotargetedandimmunotherapeuticdrugs.ThisreviewisthefirsttosummarizethelatestresearchoncircRNAsinanticancerdrugresistancebasedondrugclassificationandtodiscusstheirpotentialclinicalapplications.Keywords:CircularRNA,Cancer,Drug,ResistanceIntroductionCancerhasbecomethemostseriouspublichealthprob-lemworldwide[1].Astheearlydiagnosisofcancerur-gentlyneedstobeimproved,manypatientsarealreadysufferingfromadvancedcanceratthefirstclinicalvisit[2].Thesepatientsmisstheopportunityforsurgery,andanticancerdrugsaretheirmajortreatmentoption.Sincethefirstclinicalreportofchemotherapyforadvancedcan-cers,multipleanticancerdrugshavebeendevelopedandhaveeffectivelyimprovedtheclinicaloutcomesofpatientswithadvancedcancers[3].Inaddition,targetedandim-munotherapeuticdrugshaverecentlyusheredinanewerainmedicaltherapyforcancer[4,5].However,antican-cerdrugresistancestillcannotbeavoided,resultingincancerrelapse.Themechanismsunderlyinganticancerdrugresistancearemultifaceted.Differenthallmarkssuchastumorgrowth,selectivetherapeuticpressure,immunesystemcharacteristicsandthetumormicroenvironmentdeterminethebiologicalbehaviorsofanticancerdrugre-sistance[6].Thesehallmarksaredrivenbycomplexund...
